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| style="height:20px; width:300px; text-align:center;" |'''Friction''' acts at the point that the tyres touch the ground. The [[force]] of [[friction]] can act to [[decelerate]] the car but can also be use to [[accelerate]] the [[car]]. If there was no [[friction]] the wheels would spin but the [[car]] would not [[accelerate]].
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==Key Stage 3==
===Meaning===
'''Friction''' is a [[force]] that acts prevent two surfaces from sliding over one another.
===About Friction===
: [[Friction]] is a [[force]] so it is [[Measure|measured]] in [[Newton]]s.
: [[Friction]] is a [[Contact Force|contact force]] because it only exists when two surfaces are touching.
: [[Friction]] occurs because two [[Roughness|rough]] surfaces have bumps that fit together resisting them from sliding against each other.
{| class="wikitable"
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|[[File:SurfacesFriction.png|center|400px]]
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| style="height:20px; width:200px; text-align:center;" |The two [[diagram]] shows two [[roughness|rough]] surfaces and two [[roughness|smooth]] surfaces. The [[friction]] between the [[roughness|rough]] surfaces is greater because there are more bumps in the way to prevent the surfaces sliding against each other.
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: [[Friction]] can act to [[decelerate]] an [[object]] sliding along a surface. However, it also allows [[object]]s with a [[Driving Force|driving force]] to [[accelerate]] by preventing a wheel from sliding against the surface.
: The [[friction]] between two surfaces can be reduced with a [[lubricant]] which keeps the rough parts of two surfaces separated.
{| class="wikitable"
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|[[File:LubricantFriction.png|center|400px]]
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| style="height:20px; width:200px; text-align:center;" |The two [[diagram]] shows how [[roughness|rough]] surfaces can be separated by a [[lubricant]] reducing the [[friction]] between them.
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===Energy Transfer===
: When two surfaces slide over one another [[Work Done|work]] is done by [[friction]] to [[Mechanical Energy Transfer|transfer]] [[energy]] from the [[Kinetic Energy Store|kinetic energy store]] to the [[Thermal Energy Store|thermal energy store]] of the [[system]].
===Examples===
{| class="wikitable"
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|[[File:FrictionBowlingBall.png|center|200px]]
|[[File:FrictionCar.png|center|300px]]
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| style="height:20px; width:300px; text-align:center;" |'''Friction''' acts at the point where the bowling ball touches the ground. The [[force]] of [[friction]] acts to [[decelerate]] the bowling ball as it moves.
| style="height:20px; width:300px; text-align:center;" |'''Friction''' acts at the point that the tyres touch the ground. The [[force]] of [[friction]] can act to [[decelerate]] the car but can also be use to [[accelerate]] the [[car]]. If there was no [[friction]] the wheels would spin but the [[car]] would not [[accelerate]].
|}